const mySort = function (callback) {
  for (let i = 0; i < this.length - 1; i++) {
    for (let j = 0; j < this.length - i; j++) {
      if (callback(this[j], this[j + 1]) > 0) {
        let temp = this[j]
        this[j] = this[j + 1]
        this[j + 1] = temp
      }
    }
  }
  return this
}
Array.prototype.mySort = mySort

const arr = [5, 3, 1, 2, 4, 6]
//正序：(a,b) => a - b)
//逆序：(a,b) => b - a)
console.log(arr.mySort((a, b) => b - a))
